Made a Priceline Express booking and called Marriott's 800 number to attach my MR account to the reservation. Rep refused to do it. Called the hotel directly and that worked, so now I see the reservation on marriott.com but it does not show anything relevant to elite status.

I've searched these forums and found plenty of posts advising third-party bookers to show their card to the front desk upon check-in. Is the physical card necessary? The only elite card I've ever actually had to show was United's. In all other cases, my account number alone was enough.